Abstract

White-nose syndrome (WNS), a disease caused by the fungus Pseudogymnoascus destructans1, has spread west from New York to Missouri and has killed more than six million bats2. In bat hibernacula where WNS is present, mass mortality has been observed and there is a high potential for population collapse or extinction of some species at a regional level. Although WNS is not yet present in the western U.S. , the high diversity of bat species3 and appropriate conditions for P. destructans in area caves may put these populations at risk. The absence of WNS in western caves provides a unique opportunity to ask questions about how bat species, geographic location, and habitat shape pre-WNS microbiota. The importance of microbiota is shown in many organisms, including amphibians, where individuals that survive a chytrid infection carry a higher prevalence of Janthinobacterium lividum4. The establishment of a pre-WNS baseline microbiota of western bats is critical to understanding how P. destructans may impact the native microbiota of the bats. Previous studies5,6 that identified the microbiota of bats have focused on gut and fecal microbiota, with little attention given to the external microbiota. Here we show for the first time that there are biogeographic differences in the abundance and diversity of external bat microbiota. From our 202 (62 cave-netted, 140 surface-netted) bat samples belonging to 13 species of western bats uninfected with WNS, we identified differences in microbiota diversity among sites, and between cave bats versus surface-netted bats, regardless of sex and species. These results present novel information about the factors that shape external microbiota of bats providing new insights into potential vulnerability of different bat species to WNS.